public class Example4_8 {
  public static void main(String args[]) {
   Circle circle=new Circle();
   circle.setRadius(10);
   Circular circular=new Circular();
   System.out.println("cirlce的引用:"+circle);
   System.out.println("圆锥的bottom的引用:"+circular.bottom);
   circular.setHeight(5);
   circular.setBottom(circle);
   System.out.println("circle的引用:"+circle);
   System.out.println("圆锥的bottom的引用:"+circular.bottom);
   System.out.println("圆锥的体积:"+circular.getVolme());
   System.out.println("修改circle的半径，bottom的半径同样变化");
   circle.setRadius(20);
   System.out.println("bottom的半径:"+circular.getBottomRadius());
   System.out.println("重新创建circle，circle的引用将发生变化");
   circle=new Circle();
   System.out.println("circle的引用:"+circle);
   System.out.println("但是不影响circular的bottom的引用");
   System.out.println("圆锥的bottom的引用:"+circular.bottom);
}
}

